This invention relates to a heat-developable color photo-sensitive material in which a color-image is produced by transferring a diffusible dye formed in a heat-development process, and more particularly to a heat-developable color photo-sensitive material containing a novel dye-providing material capable of producing a diffusible dye through a heat-development process.
Photographic method using a photo-sensitive silver halide has so far been known and that is superior to the other photographic methods in photo-sensitivity, gradation and image preservability and has most popularly been put into practice.
In this method, however, a wet-process has been applied to such a processing step as a developing, fixing or washing step. There have accordingly been many problems such as that it cannot help taking a lot of time and trouble and concerning about the influence of processing chemicals on the human body or about the chemical pollution of a processing room and an operator, and further taking care of industrial waste pollution. It has therefore been demanded to develop a photo-sensitive material capable of using a photo-sensitive material therein and being applied with a dry-process.
There have been made a number of proposals of the above-mentioned dry-processing photographic methods. Among them, a heat-developable photo-sensitive material capable of being developed by a heat-treatment has now become the object of public attention.
Concerning these heat-developable photo-sensitive materials the photo-sensitive materials each comprising an organic silver salt, a silver halide and a reducing agent are disclosed in, for example, Japanese Patent Examined Publication Nos. 4921/1968 and 4924/1968.
There have been the attempts to obtain color-images in a variety of methods through the improvements on the above-mentioned photo-sensitive materials.
For example, the heat-developable color photo-sensitive materials for forming color images through the reaction of couplers with the oxidants of an aromatic primary amine developing agent are disclosed in U.S. Pat. Nos. 3,531,286, 3,761,270, 3,764,328 and the like.
In Research Disclosure, Nos. 15,108 and 15,127, the heat-developable color photo-sensitive materials are disclosed to produce color images through the reaction of couplers with the oxidants of developing agent of a sulfonamidophenol derivative or a sulfonamidoaniline derivative. In these processes, however, a reduced silver image and a color image are produced simultaneously on an exposed area after heat-developed, and the color image is made turbid, that is a problem. As for the methods of solving such a problem, there are some methods such as that a silver image is removed in a liquid process or that dyes only are transferred to other layer such as an image receiving sheet having an image receiving layer, however, there is also a problem that it is not so easy to transfer the dyes only to the image receiving sheet with the discrimination thereof from the substances remaining unreacted.
Further, in Research Disclosure, No. 16,966, there discloses a heat-developable color photo-sensitive material in which an organic imino salt having dyes as the composition thereof is used so as to split off the imino group in an exposed area through a heat-development, and a color image is produced on an image receiving layer in the form of a sheet of transfer-paper by making use of a solvent. In this process, however, there is a problem that it is impossible to obtain a sharp and clear color image because it is difficult to inhibit the splitting-off of the dyes in an area out of light.
Still further, in Japanese Patent O.P.I. Publication Nos. 105821/1977, 105822/1977 and 50328/1981; U.S. Pat. No. 4,235,957; Research Disclosure, Nos. 14,448, 15,227 and 18,137; and the like, there are disclosed the respective heat-developable color photo-sensitive materials in which a positive color image can be produced in a heat-sensitive silver dye bleach process. Wherein, there are problems that an extra processing step and photographic component material are required, such as that some sheets containing an activator for accelerating the bleach of dyes are superposed together and are then heated, and that the obtained color image is gradually reduced and bleached by a co-existing free silver or the like during a long-term preservation.
In addition to the above disclosures, there are U.S. Pat. Nos. 3,180,732, 3,985,565, and 4,022,617; and Research Disclosure No. 12533 each disclosing the heat-developable color photo-sensitive materials utilizing a leuco dyes to produce a color image. In this process, however, there is a problem that the photo-sensitive materials are gradually colored during the preservation, because it is difficult to incorporate the leuco dyes stably into the photo-sensitive materials.
In addition, Japanese Patent O.P.I. Publication No. 179840/1982 discloses a heat-developable color photo-sensitive material in which a color image pattern is formed by making use of a reducible dye-providing material capable of releasing both a dye-releasing assistant and a diffusible dye. In this method, however, it is inevitable to use the dye-releasing assistant, and this dye-releasing assistant is the so-called base or a basic precursor. There are the problems in the technique using such a base or a basic precursor, namely, fog is increased and a maximum density is lowered due to the existence of the base in the case of a heat-developable photo-sensitive material using an organic silver salt oxidizing agent.
Further, Japanese Patent O.P.I. Publication Nos. 186744/1982, 123533/1983 and 149046/1983 disclose the heat-developable color photo-sensitive materials in which a color transfer image pattern is obtained by releasing or producing a diffusible dye through a heat-development process. However, the exemplified compounds of the dye-providing materials disclosed therein have such a defect that it is hard to say that the migration of the compounds between the layers is completely prohibited during the multiple coating or heat-developing process, so that a color turbidity is apt to cause.
As disclosed in Japanese Patent O.P.I. Publication No. 149047/1983, there are the methods with the purpose of compensating the above-mentioned defect, in which a polymer is used to serve as a dye-providing material. Even the exemplified compounds described therein have the defects that, though the migration of dye-providing material is successfully prohibited, the efficiency of producing diffusible dye is substantially low and a maximum density (Dmax) of a transfer image pattern or the fog (Dmin) thereof is serious.